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Plasma dynamics and radiation characteristics of the PF-1000 facility at its upper energy limit (≈ 1 MJ) were investigated by help of a number of diagnostics with ns temporal resolution. Special attention was paid to the temporal and spatial cross correlation between plasma, electron and ion beams dynamics as well as e/m radiation but in particular in relation to the neutron emission parameters. Results of these experiments are in favor of neutron emission model based on ion beam-plasma interaction with three important features: 1) plasma target is hot and confined during a few “inertial confinement times”; 2) ions of the main part of the beam are magnetized and entrapped about the pinch plasma target for a longer period than the characteristic time of the plasma inductive storage system and accelerating diode existence; and 3) ion-ion collisions — fusion and Coulomb ones — are both responsible for neutron emission. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper we present the results obtained on the plasma focus PF-1000 in IPPLM Warsaw and on the z-pinch S-300 in RRC Kurchatov Institute in Moscow using a deuterium load. On the PF-1000 plasma-focus device with deuterium filling gas the energy of neutrons and time of their generation are determined by time-of-flight method from seven scintillation detectors positioned in the axial direction. The neutron signals (total yield ∼1011 neutrons per shot) correlate with hard x-rays and their maximum occur ∼150–200 ns after the pinch phase. The initial portion of neutron pulse has beam-target origin with downstream energies up to 2.8–3.2 MeV and the final portion of neutrons has isotropic distribution of energies in the range of 2.2–2.7 MeV. The z-pinch experiments were performed on the S-300 generator with the load formed from a deuterated CD2 fibre in the axis of a tungsten wire array. The energy of neutrons and time of their generation are determined by time-of-flight method from 5 scintillation detectors positioned in the axial and side-on direction. The neutrons with total yield up to 3×109 per shot are produced in the energy range of 1.8–3.2 MeV at 10–30 ns after the pinch phase represented by dip in the current waveform, peak of the voltage and minimum of the pinch diameter. The distribution of neutron velocities is random within the total solid angle. The neutrons in both devices are produced by a non-thermal mechanism with deuterons accelerated to the energies above 100 keV partially in anode-cathode direction and partially with almost isotropic distribution of velocities at the time of the plasma expansion, i.e. after the pinch phase. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The paper presents a summary of experimental studies of the corpuscular and X-ray emission, which were carried out with two medium-size Plasma-Focus (PF) facilities at IPJ in Swierk, Poland, during recent years. Those experiments were performed with the MAJA-PF and PF-360 devices operated within the energy range from 37 kJ to 121 kJ. The two-peak neutron emission was observed within PF-360 facility discharges. Energy of neutrons in the first pulse, as measured along the z-axis, was En = (2.65 ± 0.13) MeV, while that measured side-on was En = (2.47 ± 0.15) MeV. Electron beams were mostly generated after the maximum compression phase, while high-energy deuterons were generated earlier. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

At the signals of x-rays usually 2 peaks were observed. The first peak corresponded to the time of the minimum diameter of the imploding plasma sheath (pinch phase) recorded by the visible frames. The second peak occurred 150–200 ns later at the time of the development of instabilities. High-energy electrons registered in the upstream and downstream directions differed in the intensity (ratio 3:1) and in the time of production. Their peaks correlated with x-rays. The energy of neutrons and time of their generation were determined by time-of-flight method from the pulses of seven scintillation detectors positioned in the axial direction. At the rise-time, each neutron pulse has registered downstream energies in range of 2.7–3.2 MeV. The final part of neutron pulse has isotropic energy distribution with energies up to 2.6–2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the dense plasma in the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with existence of the structure of the dense plasma positioned at the bottom of the dilating current sheath, similarly to the first pulse. The neutrons have a non-thermal beam-target origin. A possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The paper concerns the monitoring of high-current pulse discharges and the determination of the plasma concentration within the dense magnetized plasma by means of optical spectroscopy methods. In experiments with the large PF-1000 facility operated at IPPLM in Warsaw, Poland, attention was paid to the determination of the operational mode and electron concentration under different experimental conditions. To measure the visible radiation (VR) the use was made of the MECHELLE®900-spectrometer equipped with the CCD readout. The VR emission, observed at 65° to the z-axis, originated from a part of the electrode surfaces, the collapsing current-sheath layer and the dense plasma pinch-region (40–50 mm from the electrode ends). Considerable differences were found in the optical spectra recorded for so-called “good shots” and for cases of some failures. Estimates of the electron concentration, which were performed with different spectroscopic techniques, showed that it ranged from 5.56×1018 cm-3 to 4.8×1019 cm-3, depending on experimental conditions. The correlation of the fusion-neutron yield and the plasma density was proved. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The energy of neutrons and time of their generation are determined from seven scintillation detectors positioned in the axial direction. At the onset, each neutron pulse has beam-target origin with downstream energies in range of 2.7–3.2 MeV. The final part of neutrons has isotropic energy distribution with energies up to 2.6–2.7 MeV. The evolution of the neutron pulses correlates with the visible frames. The first pulse correlates with the fast downstream zipper-effect of the axis layer of the pinch and with the forming of the radiating ball-shaped structure at the bottom of the dilating plasma sheath. The second neutron pulse correlates with the second pinching and exploding of the plasma of lower density and with the structure of the dense plasma at the bottom of the dilating current sheath, similarly to the first pulse. The possible influence of the zipper-effect on the acceleration of deuterons and on the plasma heating is discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]